The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art.
Centrifugal Pendulum Vibration Absorbers (CPVAs) are typically used to reduce torsional vibrations in rotating machine components. For example, a rotating member such as a shaft includes several CPVAs, where each CPVA has a pendulum mass that oscillates as the shaft rotates. The movement of the pendulum masses counteract torque fluctuations that are transmitted from the engine to the shaft as the shaft rotates, which reduces the torsional vibration of the shaft. CPVAs can be designed such that the oscillation frequency of the pendulum mass matches the engine combustion frequency at any engine operating speed. However, matching the oscillation frequency with the engine combustion frequency does not always provide suitable vibration reduction in automotive vehicles. This is because frequency characteristics of automotive engines in motor vehicles are influenced by axle stiffness and transmission inertias as well as engine RPM.
As a result, spring dampers are sometimes used instead of CPVAs to attenuate torsional vibrations transmitted by automobile engines. However, one drawback is that spring dampers are generally only effective within a predetermined frequency range that is often narrow. The design tradeoff of having to tune the spring dampers for a specific frequency range results in that they are generally not able to provide sufficient dampening at lower engine speeds such as when the engine operates at idle.
While current CPVAs and spring dampers achieve their intended purpose, there is a need for a new and improved vibration dampening system which exhibits improved performance from the standpoint of dampening torsional vibrations at a variety of engine speeds.